The prior art has evolved a variety of building blocks which are capable of being interlocked together to construct buildings of various shapes and sizes. Prior art interlocking blocks typically utilize upwardly projecting webs which mate with recesses provided in the bases of identical blocks. The blocks are positioned on top of and in vertical interlocking relationship with each other. The prior art is exemplified, for example, in U.S. Pat. No. 3,888,060 issued June 10, 1975 for an invention of Juan Haener; U.S. Pat. No. 2,610,503 issued Sept. 16, 1952 for an invention of Clarence C. Hall; U.S. Pat. No. 3,247,633 issued Apr. 26, 1966 for an invention of Russell F. Schultz et al; U.S. Pat. No. 3,305,982 issued Feb. 28, 1967 for an invention of Oscar Murphy Steele; and, U.S. Pat. No. 3,618,279 issued Nov. 9, 1971 for an invention of T. F. Sease. However, such prior art building blocks rely either solely or heavily upon the mating relationship between the aforesaid upwardly projecting webs and recesses to interlock the blocks together. This is disadvantageous because shear forces acting perpendicular to a wall constructed of such prior art blocks may cause the upwardly protruding webs (which, of necessity, have a relatively small surface area, as compared with that portion of the surface area of the block from which the webs project) to shear away from the remainder of the block, unless a bonding agent such as mortar or grout is used to strengthen the bond between adjacent blocks. Moveover, unless bonding agents are used, such prior art blocks are not capable of resisting forces applied horizontally or vertically in the plane of a wall constructed with such prior art blocks, which may result in damage to or destruction of the wall.
The present invention provides a simplified structural block system in which a minimal number of different types of interlocking blocks may be utilized to construct a wide variety of buildings, without the need for mortar or other bonding agents. More particularly, the structural blocks of the invention enable the construction of buildings from parallel courses of blocks which are longitudinally and transversely interlocked together and which may further be vertically interlocked with additional courses of longitudinally and transversely interlocked blocks placed on top of lower courses of interlocked blocks.